The AMH test (Anti-Mullerian Hormone) is a blood test to help the fertility doctor assess the woman's ovarian reserve. The test measures the levels of AMH in a woman's blood and is helpful in determining whether a woman has premature ovarian aging (diminished ovarian reserve) or premature ovarian failure.

What Is AMH?

The Anti-Mullerian Hormone is a substance secreted by the granulosa cells in the developing egg sacs (ovarian follicles). When a woman grows older, her number of ovarian follicles begins to decrease; therefore, the amount of AMH in the blood decreases.

A woman who has very remaining follicles will have low AMH levels and is close to menopause. A woman who has many small ovarian follicles — a condition known as polycystic ovarian syndrome (PCOS) — typically has high levels of AMH.

How AMH Is a Predictor of Ovarian Reserve?

Because AMH levels correlate with the number of ovarian follicles, the test is a good predictor of ovarian reserve. Researchers have found that women with higher concentrations of AMH have a better response to ovarian stimulation and are likely to produce more eggs for IVF (in vitro fertilization) than women with low or undetectable AMH. Also, unlike follicle stimulating hormone (FSH), the levels of AMH in the blood do not fluctuate as much; therefore the test can be done at any point during the menstrual cycle.

A low AMH indicates there is a problem with the quantity and quality of a woman's eggs. Women with low AMH tend to be "poor responders" to fertility treatment — even with high doses of fertility drugs.

It's important to ask your fertility doctor if he or she is using age thresholds when considering the AMH test because a woman's "normal" AMH range is also dependent upon age — the average AMH level in younger women is higher than the average level in older women. Therefore, a young woman with a very low AMH could have a similar level to an older woman who is considered to have an "average" AMH level for her age.

AMH only one of the tests that assesses ovarian reserve. Others include blood tests for FSH and estradiol levels, the clomiphene citrate challenge test (CCCT), and a vaginal ultrasound examination of the antral follicles.